It has been common practice for many years to equip homes with smoke detectors. In recent years various construction codes have been modified to require smoke detectors in both commercial and high and low rise residential and hotels and motels. However, most of the codes do not apply to older structures, while continuous operability of smoke and fire detectors in existing installations is never completely assured due to failure from either improper maintenance procedures or loss of power. The recent spate of fires in high rise hotels delineates the seriousness of the problem. The traveler confronting these factors has in recent times relied solely on the existing alarm systems or the local fire department for rescue from building fire, many having a mental standing rule never to stay above the eighth floor so that the extension ladders of a fire truck can reach the premises occupied.
Generally, when an alarm sounds, the building occupant has ample time to evacuate the premises or take other action to avoid the fire consequences. However, without a foolproof alarm system, such course of action cannot always be utilized. To insure an adequate alarm, many imaginative and complex systems have been proposed, but as previously noted, most builders are reluctant to retrofit older structures with such devices, and maintenance and power, either on-line or back-up, are not always operable.